This is an LED based Aquarium Light. It consists of a sheet of plexiglass with holes drilled in it to accommodate LEDs facing downward into the tank. The circuitry is above the plexi and will be waterproofed with silicone/hot glue later on. The power supply can be any transformer that you have kicking around. I used a 9.0VDC 800mA clock radio transformer.
The idea of this is to:
1) Reduce the cost of lighting your aquarium
2) Lower the heat generated by lighting
I am in no way responsible if anything goes wrong, and as with any electronics, there is a certain amount of risk involved.
I would not recommend using this on a planted tank because LED's do not have the proper spectrum.
Step 1Planning and Design
First off, you must decide how many LEDs you are going to install, and how to install them. I decided to use a 18x3 grid of LEDs. For my 10g tank (20" long), I chose to start the LEDs 1" in from each end of the tank and a 1" space between LEDs. Your design will most likely vary. You also must consider the fact that resistors are needed when working with LEDs. I had
this site recommended to me and I found it to be VERY useful. You must know what voltage and current your transformer will put out. You also must have your LEDs chosen and know the voltage and current required by them.
If you drill your holes at an angle you can even angle them to get more even lighting across larger tanks without having to use a wider set up or if you wanted to replace a light in a current hood light.
Also, for anyone that may not know Led lights, resistors, jumper wires, breadboard, circuit boards and extra wire, and even you transformer can be found at Radioshack.
The angle idea is great, but the light from LED's doesn't penetrate water very well, so I would want them to be pointing down to reach the bottom of the tank.
I debated installing some blue LED's, but I run my tank lights off a timer and the timer just shuts off power to the transformer. If you manually turn your lighting on and off, that would work great.
Your best bet is to check the yellowpages for electronics shops, specifically stores that sell electronic components. Just start calling around and ask if they carry individual LED diodes in the colour you want, and if so how much would it be for the number you need.
So basically the transformer plugs into the wall outlet and provides DC current to power the LED's. I used one from a clock radio that outputs 9V, but you can use any one that is between ~6-12V. Just adjust the resistor values for that voltage.
I don't think you would want to dim the LED's. If you ever wanted to, however, the 555 is the best way to go. Just connect the 555 output to a transistor that can handle the load of the entire array. You don't want to use a current limiting pot, they just burn up.
As for the corrosion, I've been thinking and I believe the best way to prevent corrosion would be to encase the top in a plastic cover. Even just part of a garbage bag ballooned over the top and sealed around the edges would probably work.
If you want to be sure, just put some rice inside the cover before you seal it up. Rice acts just like those silica gel packets to dry out electronics when you buy them.
Did you find that the plexi sagged in the middle and is that the reason why the tank has is drained a bit from the top?